Engine

ABSTRACT

A rotary fluid engine powered by externally pressurized working fluid including a rotor and a plurality of swinging arms positioned to engage with and impart a torque force to the rotor when the arms are driven sequentially inward by the selective admission of charges of externally pressurized working fluid. A first segment on the rotor surface engages the free end of each arm as the arm is driven inwardly and a second segment on the rotor surface operates to return the arm outwardly after the power impulse is completed. Valving and conduit means are provided to control the direction of the working fluid to the arms and exhaust means are provided to exhaust spent working fluid from the engine. In one embodiment, the valving and conduit means are adapted to direct charges of externally pressurized working fluid sequentially against said arms so that the engine operates as a simple engine. In a second embodiment, the valving and conduit means are adapted to direct charges of externally, pressurized working fluid first against one of said arms at a high pressure and secondly against another arm at a relatively lower pressure so that said engine operates as a compound engine. In a third embodiment, transfer valve means are provided which permit said engine to be switchable between said simple and compound modes of operation. The rotor surface may include a plurality of said first and second segments so that each arm will transmit a corresponding plurality of power impulses to the rotor for each complete rotor revolution.

United States Patent [191 Hinckley ENGINE [76] Inventor: John N. Hinckley, Beloit, Wis.

[22] Filed: July 24, 1972 [21] Appl. No.: 274,202

Related US. Application Data [60] Division of Ser. Nos. 860,684, Sept. 24, 1969, Pat. No. 3.684.413. which is a continuation-in-part of Ser. No. 812.656. April 2. 1969. abandoned.

[52] U.S. Cl 418/12, 418/141, 418/250 [51] Int. Cl. F0lc 11/00 [58] Field of Search 123/827, 8.41, 8.23, 8.39;

Primary Examiner-C1arencc R. Gordon Attorney, Agent, or Firm-Melvin F. Jager [57] ABSTRACT Arotary fluid engine powered by externally pressurized working fluid including a rotor and a plurality of 378 HPA 302 [451 July 16,1974

swinging arms positioned to engage with and impart a torque force to the rotor when the arms are driven sequentially inward by the selective admission of charges of externally pressurized working fluid. A first segment on the rotor surface engages the free end of each arm as the arm is driven inwardly and a second segment on the rotor surface operates to return the arm outwardly after the power impulse is completed. Valving and conduit means are provided to control the direction of the working fluid to the arms and exhaust means are provided to exhaust spent working fluid from the engine. In one embodiment, the valving and conduit means are adapted to direct charges of externally pressurized working fluid sequentially against said arms so that the engine operates as a simple engine In a second embodiment, the valving and conduit means are adapted to direct charges of externally, pressurized working fluid first against one of said arms at a high pressure and secondly against another arm at a relatively lower pressure so that said engine operates as a compound engine. In a third em bodiment, transfer valve means are provided which permit said engine to be switchable between said simple and compound modes of operation. The rotor surface may include a plurality of said first and second segments so that each arm will transmit a corresponding plurality of power impulses to the rotor for each complete rotor revolution.

3 Claims, 4 Drawing Figures PATENTEDJUL 1 51914 SHEU 1 BF 3 Non a: Dun

OOn

ENGINE This application is a division of my application Ser. No. 860,684, filed Sept. 24, 1969 now US. Pat. No. 3,684,413 issued Aug. 15, 1972 which in turn is a continuationin-part of my application Ser. No. 812,656, filed Apr. 2, 1969, entitled ENGINE", now abandoned and assigned to the same assignee as the present invention.

The present invention relates to an improved prime mover and more particularly relates to an improved rotary engine which is powered by externally pressurized working fluid and is capable of replacing or supplementing conventional reciprocating piston internal combustion engines.

As well-known to those skilled in the art, the internal combustion engine in current use has many inherent disadvantages which have caused considerable concern about the continued use of that type of an engine as the dominant prime mover. For instance, two principal disadvantages of internal combustion reciprocating piston engines are low thermal efficiency and poor pollutant emission characteristics. These disadvantages result mainly from the inability of the engine to utilize the fuel effectively or to complete'the combustion of the fuel within the expansion chamber of the engine before exhausting the spent fuel to the atmosphere. Another disadvantage of reciprocating piston engines in current use is inherently low overall mechanical efficiency. It is well-known, for instance, that the overall efficiency of piston engines is suppressed to approximately 25 percent by such factors as the inability of the pistons to produce power for about the first 30 and last 40 of each stroke, and the need for power-absorbing static and dynamic counterbalancing, and parasitic auxiliary systems.

Many attempts have been made to improve upon the thermal characteristics of reciprocating piston engines. These attempts have included such efforts as major engine redesign to increase the fuel combustion during expansion, and suppression of exhaust emissions with parasitic equipment, such as regenerators and the like. Despite the success of some of these efforts, most reciprocating engine designs continue to require expensive fuels and continue to have unacceptably high pollution characteristics. Efforts to improve the characteristics of reciprocating engines have also led to complicated designs which are expensive to manufacture, operate and maintain, and which continue to have an unsatisfactorily low mechanical efficiency.

The present invention overcomes the abovementioned problems of reciprocating piston engines by providing a rotary engine which is powered by externally pressurized working fluid and is capable of operating with substantially improved mechanical and thermal efficiencies and substantially improved antipollution characteristics. The rotary engine of the present invention also has a high horsepower-to-weight ratio and can produce high torque with a smooth and continuous flow of power to the output shaft. The structural and functional characteristics of this improved rotary engine also permit great flexibility of operation, thereby allowing the engine to be adapted for a variety of applications.

The rotary engine is adapted for use in a power system having a continuous source of working fluid and means for pressurizing the working fluid outside of the engine. The system also includes means for feeding charges of such externally pressurized working fluid into the engine so that the pressurized fluid expands in the engine and creates a torque force which drives the engine output shaft. The externally pressurized working fluid may comprise a compressed gas such as compressed carbon dioxide, in which case the power system is provided with means for maintaining the gas under pressure. Alternatively, the externally pressurized working fluid may be a pressurized vapor such as superheated steam, and the power system provided with an external heat source, such as a boiler, for creating the pressurized vapor. Similarly, the power system including the engine may use an open fluid cycle wherein the working fluid is exhausted to the atmosphere after expansion in the engine, or may use a closed fluid cycle which recirculates the working fluid through the system.

EXEMPLARY EMBODIMENT Additional objects and features of the present invention will become apparent from the following description of an exemplary embodiment. In the illustrated embodiment, the engine is adapted as a Rankine cycle engine having a closed fluid system wherein energy is added to the pressurized working fluid by the application of external heat. Superheated steam is the preferred working fluid for the illustrated system, but it will be appreciated by those skilled in the art that alternative working fluids such as mercury or organic compounds reduced to vapor can be utilized with equal effectiveness in such a vapor cycle system. In the illustrated embodiment, the engine rotor is provided with double opposed lobes, and the engine is adapted so that each arm transmits two power impulses to the rotor for each rotor revolution.

The standard components of the Rankine cycle system, such as the fluid reservoir, the vapor generator for creating the externally pressurized working fluid, the condenser, valves, pumps and heaters, have been excluded from the disclosure for purposes of simplicity. The operation of such components to create the pressurized working fluid, such as by converting water vapor to superheated steam by the application of external heat, and to circulate the working fluid to and from the engine are well-known and therefore need not be described in detail.

In the drawings:

FIG. 1 is a partial cross-sectional end view of an engine assembly formed from dual engine units which incorporate a double-lobe rotor and which are crosscoupled and offset to form a balanced compound external combustion engine;

FIG. 2 is a cross-sectional side view of the compound external combustion engine assembly illustrated in FIG. 9, as viewed along the line 22 in FIG. 1;

FIG. 3 is a cross-sectional end view of the engine assembly illustrated in FIGS. 1 and 2 schematically showing the valving and manifold systems which adapt the engine assembly for a compound mode of operation; and I FIG. 4 is a cross-sectional end view of the engine illustrated in FIGS. 1 and 2 schematically showing the valving and manifold systems which adapt the engine for a simple mode of operation.

FIGS. 14 illustrate a engine assembly 300 which is adapted to be switched selectively between a simple and a compound mode of operation. The assembly 300 is formed from dual engine units'300A and 300B which are coupled together about a common drive shaft 310.

The units 300A-B include rotor housings 320A and B, respectively, which, as illustrated in FIG. I, are offset on the shaft 310 by a 45 angle. Further, each of the engine units 300A and B contains four swinging abutment arms 340A-D and 340E-l-l, respectively, which are uniformly spaced in the associated rotor housings, on suitable pivot pins 341. Double-lobe rotors 350A and 3508 are also mounted in the generally cylindrical rotor chambers defined by the housings 320A and 320B, respectively. As indicated in FIGS. 9 and 10, theserotors 350A and B are connected to the common drive shaft 310 in an offset relationship, so that the rotors are 90 out-of-phase with each other. The connections for the rotors 350A and B, as well as for the arms 340, comprise splines 351 or the like which permit the arms and rotors to float freely in the lateral direction,

and be self-centering within the associated housings 320.

As illustrated in FIG. 2, the outer ends of the housings 320A and B are closed by valve housings 370A and B, respectively. Each valve housing includes a main bearing 371 which supports the drive shaft 310, and an end plate 372. The end plates 372 seal the adjacent end of the rotor housing, and support the pivot pins 341 (FIG. 9) about which the arms 340 rotate. A removable cover plate 380 seals each valve housing from the dirt and dust usually found at engine installations.

The valve housings 370A and B also include manifold and valving systems for controlling the admission of pressurized working fluid into the rotor housings 320A and B. In this regard, a plurality of admission chests 374 are arranged uniformly around the associated housing 370A and 3708 so that the chests are spaced adjacent the swinging arms 340A-H. Pressurized working fluid such as superheated steam or the like can be directed from a vapor generator (not shown) or other suitable source of high pressure fluid to the admission chests 374 through associated intake pipes 375. Manifolds 376 are also incorporated in the valve housings and are arranged in fluid communication with the intake pipes 375 and with a high pressure expansion chamber HP associated with the adjacent swinging arm v340. Timing and metering of the incoming pressurized fluid is accomplished by separating the admission chests 374 from the associated intake manifold 376 by means of a'poppet valve 377. The stroke for each valve 377 is controlled by cams 378 connected to the drive shaft 310 and by a conventional gearing mechanism such as a Stephenson-type variable gearing mechanism cent ends of the rotor housings.

As illustrated in FIG. 2, the rotors 350 and the arms 340 have approximately the same width as the rotor housings 320, to providea large surface area for contact with the expanding working fluid, and to space the rotors and arms within a very close tolerance to the end plates 362 and 372. The rotors and arms of the engine assembly 300 can thereby be sealed with respect to these plates 362 and 372 by providing-a plurality of discontinuous labyrinth grooves 352 on the side portions of the rotors 350, and similar grooves 342 on the side portions of the arms. The grooves 342 and 352 follow the profile of the associated arms and rotors, and

act as check valves to stop the flow of working fluid.

past the rotors and arms. The arms 340, the rotors 350, and the housings 360 and 370 are preferably designed to have substantially equal coefficients of expansion, so that the operation of the labyrinth scaling is unaffected by engine load or operating temperature.

Each of the swinging arms 340Al-l includes a bevportion 347 which provides clearance for the rotor to pass by the arms.

As illustrated clearly in FIG. 1, each of the arms 340A-H define integral wedge-shaped horn members 348. Each horn 348 is adjacent the free end of the arm and is spaced so that the arm defines a substantial contact surface 344. The front edge 349 on each of the horns 348 is curved to be concentric with the arm pivot pin 341, and extends outwardly from the arm for a distance which exceeds the length of the inward arm stroke.

Conforming wedge-shaped recesses 328 in the rotor housings 320A and B receive the adjacent horn 348 when the associated arm 340 is in its outermost posi tion. An arcuate wall 329 of each recess 328 is positioned to form a seal with the curved edge 349 on the arm 340 as the arm moves inwardly toward the rotor 350.

The recesses 328 thereby provide a sealed chamber which expands in volume as the associated arm 340 moves inwardly toward the adjacent rotor 350. These expanding chambers are in direct fluid communication with the adjacent intake manifold 376, and define high pressure chambers HR for each of the arms 340A-H, respectively. By this arrangement, each chamber HR is adapted to receive a charge of pressurized working fluid from the admission chest 374.

The engine assembly 300 also includes low pressure chambers LP spaced adjacent the contact surface 344 on the free end of each of the arms 340A-I-l. These chambers LP are adapted to receive a charge of working fluid, such as steam or the like, for expansion against the associated arm contact surface 344 and rotor 350. As seen by the positions of the arms 3408 and D in FIG. 1, the arm horns 348 operate to seal the high pressure chambers HP from the low pressure chambers LP during the operation of the engine assembly 300.

The transfer housing 360 also includes a plurality of compound transfer channels 364 which join an expandable high pressure chamber HP of one engine unit 300A or B in communication with a low pressure chamber LP of the opposite engine unit. As illustrated schematically in FIG. 3, the channels 364 thereby permit the transfer of working fluid between the engine units 300A and B when the engine assembly 300 is operated as a compound engine.

The housing 360 similarly includes a plurality of simple" transfer channels 302 which adapt the engine assembly 300 for a simple mode of operation. As schematically illustrated in FIG. 4, the simple channels 302 connect each high pressure chamber HP (e.g., HP into direct fluid communication with the low pressure chamber LP (e.g., LP associated with the same arm 340A-H. By this arrangement, a charge of pressurized working fluid can be admitted into the high pressure chambers HP, and will simultaneously fill the transfer channel 302 and the low pressure chamber LP adjacent the same arm 340. The charge can then expand simultaneously against the same arm 340 in both the high pressure chamber HP and the low pressure chamber LP, when the engine assembly is operated as a simple engine.

The transfer housing 360 for the switchable engine 300 further includes a plurality of standard three-way transfer valves 304, spaced uniformly about the housing 360. Each valve 304 is placed in direct fluid communication with one of the low pressure chambers LP,, and with the associated compound and simple transfer channels 364 and 302, respectively. The transfer valves 304 can be operated manually or automatically to switch the engine 300 between a compound mode of operation, when the low pressure chambers LP are connected to the compound transfer channels 364 (FIG. 3), and a simple mode, when the low pressure chambers LP are connected to the simple transfer channels 302 (FIG. 4).

The double-lobe rotors 350A and B are identical in construction, and each include symmetrical and diametrically opposed high dwell segments 354. As indicated by the positions of the arms 340A and 340C in FIG. 1, the rotor segments 354 will sequentially engage with the four arms 540 in the same engine unit 300A and B, and maintain the arms in their outermost position for a time period defined by a selected degree of rotor rotation, e.g., 30 to 40. Furthermore, two symmetrical and diametrically opposed fall segments 356 are provided on the periphery of the rotors 350A and B, immediately following the high dwell segments 354. The segments 356 are shaped to engage the bevelled arm surfaces 343 and move the arms 340 with approximately simple harmonic motion during the inward power stroke for each arm. In the preferred arrangement, the segments 356 allow the arm 340 to move inward for approximately 60 to 70 of rotor rotation.

the fall segments 356 terminate on the rotor periphery in diametrically opposed low dwell segments 357. As illustrated in FIG. 1, the low dwell segments 357 are adapted to engage with the inwardly moving arms 340, for approximately 5 to of rotor rotation, to slow the arms for a reversal of direction. The remaining segments of the rotors 350A and B comprise rise segments 358 which engage with the arms 340 immediately following the low dwell segments 357. These rise segments 358 are shaped to return the engaged arms 340 outwardly from their innermost positions to their outermost positions with substantially harmonic motion, as the rotors 550 rotate through approximately 70 to 90 The high dwell segments 354 will then engage the arms 340, and again retain the arms in their outermost positions.

Since the double-lobe rotors 350 are symmetrical, each arm 340 will move along the rotor periphery from one low dwell segment 357 to the other low dwell segment as the rotor rotates through 180. Hence, each arm will have two complete cycles of operation for each 360 rotation of the rotors 350. Further, since the four arms 340A-D and 340E-H are uniformly spaced in the engine units 300A and B, the rotors will rotate through a 90 are between the cycles of adjacent arms, such as the arms 340A and B, in the same engine unit. The offset relationship between the two rotors 350A and 3508 and the two engine units 300A and 3008 assures that the cycles for the arms 340A-D will overlap the cycles for the arms 340E-H by 45 of rotor rotation.

The rotors 550A and B are also arranged so that the movement of arms joined by the compound transfer channels 364 (e.g., arms 340A and 340E) will transfer a charge of fluid such as steam from the high pressure chamber HP in one engine unit to the connected low pressure chamber LP in the other engine unit without performing any substantial work on the fluid. To accomplish this, the rise segments 358 and fall segments 356 are positioned to start the outward movement of the arm 340 associated with the high pressure chamber HP as the arm 340, in the other engine unit, associated with the connected low pressure chamber LP, begins its inward power stroke. The change in volume of the connected high and low pressure chambers will therefore occur at substantially the same rates, and the charge of working fluid will be transferred by the motion of the arms without performing any substantial work on the fluid. The volume of the low pressure chambers LP is preferably between 1 /2 to 2 times the volume of the connected high pressure chambers HP. However, this volume ratio may be varied over a broad range by adjusting the configuration of the arms 340 and rotors 350A and B.

The switchable engine assembly 300 also includes a plurality of exhaust ports 390A-H for exhausting the spent working fluid from the high pressure chambers HP and low pressure chambers LP. As illustrated in FIGS. 9 and 10, the central transfer housing 360'ineludes an exhaust manifold 391 connecting each of these ports 390A-H to a suitable exhaust system which can either recirculate the working fluid or discharge the fluid to the atmosphere.

The exhaust ports 390A-H are positioned in the end plates 362 of the housing 360 sothat one exhaust port is placed in a predetermined position with respect to each of the arms 340AH (e.g., the port 390A is positioned adjacent the free end of the arm 340A, etc.). By this arrangement, the ports 390A-H will receive the exhaust fluid from the arms 340A-H, respectively.

Hence, the ports 390 will open and close sequentially as the associated rotors 350 rotate in the rotor housings 320.

Moreover, as shown in FIG. 1, the ports 390 are arranged in a pattern in the respective engine units 300A and B so that the ports 390A-H are closed by the rotors 350 as the associated arms 340A-H, respectively, move inwardly against the adjacent rotor (e.g., the port 390A is closed by the rotor 350A as the associated arm 340A is moving inwardly, etc. Continued rotation of the rotors 350 will open the ports 390A-H shortly before the associated arms 340A-H engage with the rise segments 358 on the associated rotor 350. By this arrangement, ports 390 will be opened by the rotors 350 before any outward movement of the associated arm 340 starts to work against the expanded fluid. Further rotation of the rotors 350 will then force the expanded fluid out of the engine assembly 300 through the open ports 390 and the associated manifold 391.

To operate the switchable engine assembly 300 as a simple engine, the three-way transfer valves 304 (F IG. 2) are adjusted to cut off the compound transfer channels 364 from the low pressure chamber LP,, and connect the low pressure chambers with the simple transfer channels 302. The valves 304 thereby place each low pressure chamber LP in direct fluid communication with the high pressure chamber HP associated with the same arm 340A-H. A charge of fluid admitted through the cut-off valves 37''! will therefore simultaneously expand in the connected high and low pressure chambers, and transmit a substantially high torque force to the associatedarm 340 and the rotor 350.

During the operation of the engine assembly 300, the valve gear mechanisms 379 can be adjusted to control the cutoff of the working fluid admitted into the engine 300 from between a few degrees of rotor rotation up to 90 of rotor rotation. The valve mechanisms 379 are further timed to admit a charge of high pressure steam or the like through the steam chests 374 of a pair of diametrically opposed arms 340 simultaneously, as the high dwell segment 354 of the associated rotor 350 passes the free end of the pair of arms. Hence, the pairs of arms 340A and C, 3408 and D, 340E and G, and 340F and H will operate together to transmit a double power stroke to the fall segments 356 of the associated rotor 350 twice for each revolution of the shaft 310.

The inward power strokes of the pair of arms, such as arms 340A and 340C, continue as the associated rotor 350 rotates through approximately 60 to 70.

The pair of :arms 340 then engage with the low dwell segments 357 and change their direction of movement. After the rotor550 has rotated 90", the rotor rise segmenfs 358 engage with the pair of arms 340 to return the arms to their outward positions. At the same time, the following pair of arms, such as arms 3408 and 340D, aredriven inwardly against the rotor fall segments 356. The outward arm movement transfers the expanded working fluid from the high pressure chambers HP of those arms, through the channels 302, into the connected low pressure chambers LP. The spent working fluid is then exhausted from the engine unit through the exhaust ports 390 which were opened by the rotation of the associated rotor 550. As an example, as seen in FIG. 1, the rotation of the rotor 350A will open the ports 390A and C as the arms 340A and C start to move outward, and force the spent working fluid into the low pressure chambers LP, and LP from the high pressure chambers HP, and HP The fluid is then exhausted through the ports 390A and C, respectively, by the scavenging action of the rotor 350.

Both of the dual engine units 300A and B operate simultaneously in the above-described manner. However, the double power strokesof the arms 340A-D overlap with the double power strokes of the arms The engine unit 300, as a simple engine will transmit a substantial torque force to the common shaft 310, since the two double-lobe rotors 350 and eight swinging arms 340 create sixteen power strokes for each shaft revolution. The improved power output of the assembly 300, compared to conventional piston engines, is illustrated by a computerized example of the operation of an assembly 300 made from dual engine units which each had a 7 /2 inch internal diameter and a 4 inch width. The assembly was adjusted for a simple mode of operation with superheated steam, and the initial steam pressure was set at 200 psig. With the steam cutoff mechanism 37 9 set for 90 of rotor travel before cut off, the projected characteristics of the assembly were a steam exhaust pressure of 196 psig; a means torque of 25,462 inch-pounds; and an output of 485 indicated horsepower at 1,200 rpm. Similarly, with the steam cutoff set for 45 of rotor travel, the projected exhaust pressure was 75 psig; the mean torque was 21,105 inch-pounds; and the output was 402 indicated horsepower at 1,200 rpm.

To operate the engine assembly 300 as a compound engine, the three-way transfer valves 304 (FIG. 2) are adjusted to connect the low pressure chambers LP with the compound transfer channels 364. This arrangement will cause the charges of high pressure fluid admitted into the high pressure chambers HR to be expanded in those high pressure chambers and then transferred through the channels 364 to the connected low pressure chambers LP,, in the opposite engine unit. The full energy of the working fluid will thus be utilized by compounding the fluid expansion with the charges first expanded at high pressure in the chambers HP, and then at low pressure in the connected low pressure chambers LP.

With the three-way valve 304 arranged for a compound'mode of operation, the operation of the engine assembly 300 is begun by adjusting the valve gear mechanisms 379 to admit high pressure steam or the like into the high pressure chambers HP through steam chests 374A-H, at the desired rate. As described above, the mechanism 379 can be set to adjust the steam cutoff from a few degrees of rotor rotation up to of rotor rotation. The admission of the steam charges is timed so that charges simultaneously enter the high pressure chambers HP associated with diametrically opposed arms in each of the engine units 300A and B (e.g., the arms 340A and C; and the arms 3408 and D). The charges will thereby drive the opposed pair of arms 340 inwardly against the fall segments 356 of the associated rotor 350 and create a double power stroke on the rotor.

The continued rotation of the associated rotor 350 will engage the inwardly moving pair of arms first with the rotor dwell segments 357 and then with the rise segments 358. The pair of arms, such as 340B and 340D, are then driven outwardly by the rotor 350, and thereby decrease the volume of the associated high pressure chambers HP. Simultaneously, the fall segments 356 on the rotor 350 in the opposite engine unit will engage with pair of coupled arms 340 in that unit (e.g., 340E and 340G, coupled to the arms 340A and C by the channels 364). The outward movement of the arms 340 in one engine unit will transfer the charge of working fluid from the associated high pressure chambers HP through the transfer channels 364 and into the connected low pressure chambers LP in the opposite engine unit. For example, the outward'movement of the arms 340A and 340C will transfer the working fluid from the high pressure chambers HP,, and C into the low pressure chambers LP and After such fluid transfer, the charge can expand a second time in the low pressure chambers LP against the adjacent arms 340, at the same time as a separate fresh charge of fluid is expanded in the high pressure chamber HP of the same arm 340. The continued rotation of the rotors 350 will open the adjacent exhaust ports 390, and the spent fluid charge then will be exhausted from the low pressure chambers LP through the open ports 390.

The characteristics of the engine assembly 300, when operated as a compound engine, were determined by computer calculations for an assembly having dual units with 7 /2 inch internal diameters and 4 inch widths. The initial superheated steam pressure was 200 psig. When the admission of steam was cut off at 90 of rotor rotation, the exhaust pressure was 97 psig; the mean torque equaled 13,256 inchpounds, and the output was 253 indicated horsepower at 1,200 rpm. When the steam cutoff was set at 45 of rotor rotation, the exhaust pressure was 64psig; the mean torque equaled 10,972 inch-pounds, and the output was 209 indicated horsepower at 1,200 rpm.

Although the invention has been described above with a certain degree of particularity with respect to several embodiments, it should be understood that this disclosure has been made only by way of example. Consequently, numerous changes in the details of construction and in the combination and arrangement of the components as well as the possible modes of utilization for the rotary engine in accordance with this invention will be apparent to those familiar with the art, and may be resorted to without departing from the scope of the invention.

What is claimed is:

l. A power assembly formed from dual externally pressurized fluid engines joined to a common output shaft comprising:

a housing surrounding a central output shaft and defining a pair of generally cylindrical rotor chambers having end walls;

a pair of double-lobe rotors mounted on said shaft so that one of said rotors is positioned in each of said rotor chambers and so that said rotors are offset 90 on said shaft, each of said rotors having a substantial transverse surface and side portions spaced adjacent said end walls;

four elongate arms positioned uniformly within each of said rotor chambers, with each arm having side portions spaced adjacent said end walls and further having one end pivoted to said housing and the other end free to swing between an outward position engaged with said housing and an inward position engaged with the surface of the associated rotor in said chamber, said four arms in one rotor chamber being offset 45 in said housing with respect to the four arms in said other rotor chamber;

each of said rotors including a pair of diametrically opposed first rotor segments defined by the rotor periphery to sequentially engage with the free ends of an opposed pair of the associated arms and permit said engaged pair of arms to move inward and transmit a torque force to said rotor;

each rotor further including a pair of diametrically opposed second rotor segments sequentially engageable with the free ends of an opposed pair of associated arms to return said engaged pair of arms to said outward position;

a tapered horn member provided on each of said arms adjacent said free arm end and projecting outwardly into an arm recess in said housing, each of said horn members having outwardly converging edges with one edge being positioned to slide in sealing engagement with said housing within the associated arm recess as said arm moves between said inward and outward positions;

- a plurality of first expandable fluid chambers defined by said housing adjacent the free end of each of said arms;

a plurality of second expandable fluid chambers defined by said arm recesses and the associated arms and sealed from said first chambers by said arm horn members; v

means to connect said second fluid chambers to a source of externally pressurized working fluid;

valve means operable to sequentially direct charges of said pressurized working fluid into said second chambers so that said fluid will operate within said second chambers and forcefully urge a pair of opposed arms inwardly against the opposed first segments'of the adjacent rotor and thereby impart a torque force to said rotor and shaft;

transfer channel means connecting each of said second chambers in one of said rotor chambers to the axially adjacent first chamber in the opposite rotor chamber to transfer charges of working fluid from said second chambers into said connected first chambers in response to the change of volume of said connected chambers caused by the movement of the associated arms, whereby the operation of said charges can be compounded in said first and second chambers and said engine operated as a compound engine;

exhaust means in fluid communication with each rotor chamber and arranged so that rotation of said rotor opens said exhaust means and forces the fluid charges from said first chambers through said exhaust means; I

and means sealing said side portions of each of said rotors and arms with respect to the adjacent housing end walls.

2. A rotary engine in accordance with claim 1 wherein said arms and rotors are free to slide transversely within the associated rotor chambers and wherein said means sealing said rotors and arms with respect to said end walls comprises a plurality of discontinuous labyrinth grooves provided in the side portions of said rotors and arms.

3. A rotary engine in accordance with claim 1 wherein the change of volume in the connected first and second chambers occurs at substantially the same rate so that the fluid charges are transferred from said second to said first chambers without performing substantial work on the fluid. 

1. A power assembly formed from dual externally pressurized fluid engines joined to a common output shAft comprising: a housing surrounding a central output shaft and defining a pair of generally cylindrical rotor chambers having end walls; a pair of double-lobe rotors mounted on said shaft so that one of said rotors is positioned in each of said rotor chambers and so that said rotors are offset 90* on said shaft, each of said rotors having a substantial transverse surface and side portions spaced adjacent said end walls; four elongate arms positioned uniformly within each of said rotor chambers, with each arm having side portions spaced adjacent said end walls and further having one end pivoted to said housing and the other end free to swing between an outward position engaged with said housing and an inward position engaged with the surface of the associated rotor in said chamber, said four arms in one rotor chamber being offset 45* in said housing with respect to the four arms in said other rotor chamber; each of said rotors including a pair of diametrically opposed first rotor segments defined by the rotor periphery to sequentially engage with the free ends of an opposed pair of the associated arms and permit said engaged pair of arms to move inward and transmit a torque force to said rotor; each rotor further including a pair of diametrically opposed second rotor segments sequentially engageable with the free ends of an opposed pair of associated arms to return said engaged pair of arms to said outward position; a tapered horn member provided on each of said arms adjacent said free arm end and projecting outwardly into an arm recess in said housing, each of said horn members having outwardly converging edges with one edge being positioned to slide in sealing engagement with said housing within the associated arm recess as said arm moves between said inward and outward positions; a plurality of first expandable fluid chambers defined by said housing adjacent the free end of each of said arms; a plurality of second expandable fluid chambers defined by said arm recesses and the associated arms and sealed from said first chambers by said arm horn members; means to connect said second fluid chambers to a source of externally pressurized working fluid; valve means operable to sequentially direct charges of said pressurized working fluid into said second chambers so that said fluid will operate within said second chambers and forcefully urge a pair of opposed arms inwardly against the opposed first segments of the adjacent rotor and thereby impart a torque force to said rotor and shaft; transfer channel means connecting each of said second chambers in one of said rotor chambers to the axially adjacent first chamber in the opposite rotor chamber to transfer charges of working fluid from said second chambers into said connected first chambers in response to the change of volume of said connected chambers caused by the movement of the associated arms, whereby the operation of said charges can be compounded in said first and second chambers and said engine operated as a compound engine; exhaust means in fluid communication with each rotor chamber and arranged so that rotation of said rotor opens said exhaust means and forces the fluid charges from said first chambers through said exhaust means; and means sealing said side portions of each of said rotors and arms with respect to the adjacent housing end walls.
 2. A rotary engine in accordance with claim 1 wherein said arms and rotors are free to slide transversely within the associated rotor chambers and wherein said means sealing said rotors and arms with respect to said end walls comprises a plurality of discontinuous labyrinth grooves provided in the side portions of said rotors and arms.
 3. A rotary engine in accordance with claim 1 wherein the change of volume in the connected first and second chambers occurs at substantially the same rate so that the fluid charges are transferred from said second to said first chambers without performIng substantial work on the fluid. 